End down detecting means for automatic yarn piecing apparatus

ABSTRACT

First and second photoelectric units mounted upon the carriage of an automatic yarn piecing apparatus movable along a textile spinning frame respectively detect whether the carriage is adjacent a yarn delivery zone of the spinning frame and whether yarn is present within each such zone. Variations from a preestablished norm in the photoelectric outputs of the units are converted into signals directed to a correlating circuit which includes a bistable memory device. The correlating circuit is effective to actuate a nand-gate type of control device that initiates a cycle of operation of the piecing apparatus when the carriage is in operative adjacent relationship to a yarn delivery zone wherein no yarn is detected. The correlating circuit may be temporarily disabled when desired, by inhibiting its memory device and as when the carriage of the piecing apparatus moves past an end of a spinning frame, to negate the possibility of a piecing operation being then inadvertently initiated. Inexpensive, durable and compact electrical components and circuits are employed to conserve space, to minimize manufacturing cost and maintenance, and to insure consistently reliable operation under adverse operating conditions. The successful use of a conventional phototransistor and light source in the photoelectric yarn-detection unit is achieved by restrictively limiting the vision of the phototransistor to a particular area of the spinning frame and by subjecting its electrical output to high-gain amplification, preferably in the approximate order of 50,000 times, prior to signal-conversion thereof.

United States Patent [191 Drake June 26, 1973 END-DOWN DETECTING MEANS FOR AUTOMATIC YARN PIECING APPARATUS [75] Inventor: William II. Drake, Clemson, S.C.

[73] Assignee: Maremont Corporation, Chicago, Ill.

[22] Filed: Oct. 26, 1971 [21] Appl. No.: 192,210

[52] US. Cl. 57/34 R, 57/81, 250/219 R [51] Int. Cl D011! 15/00 [58] Field of Search 57/34 R, 52, 53,

[56] References Cited UNITED STATES PATENTS 3,486,319 12/1969 Lee, Jr. et a1 57/34 R 3,498,039 3/1970 Kent et al. 57/34 R 3,638,412 2/1972 Rebsamen 57/52 3,659,409 5/1972 Saunders 57/34 R 3,672,143 6/1972 Whitney 57/53 3,680,298 8/1972 Saunders... 57/34 R 3,680,299 8/1972 Lee, Jr....... 57/34 R Primary Examiner-John Petrakes Attorney-Joseph H. Heard 5 7 ABSTRACT First and second photoelectric units mounted uponthe carriage of an automatic yarn piecing apparatus movable along a textile spinning frame respectively detect whether the carriage is adjacent a yarn delivery zone of the spinning frame and whether yarn is present within each such zone. Variations from a preestablished norm in the photoelectric outputs of the units are converted into signals directed to a correlating circuit which includes a bistable memory device. The correlating circuit is effective to actuate a nand-gate type of control device that initiates a cycle of operation of the piecing apparatus when the carriage is in operative adjacent relationship to a yarn delivery zone wherein no yarn is detected. The correlating circuit may be temporarily disabled when desired, by inhibiting its memory device and as when the carriage of the piecing apparatus moves past an end of a spinning frame, to negate the possibility of a piecing operation being then inadvertently initiated. Inexpensive, durable and compact electrical components and circuits are employed to conserve space, to minimize manufacturing cost and maintenance, and to insure consistently reliable operation under adverse operating conditions. The successful use of a conventional phototransistor and light source in the photoelectric yam-detection unit is achieved by restrictively limiting the vision of the phototransistor to a particular area of the spinning frame and by subjecting its electrical output to high-gain amplification, preferably in the approximate order of 50,000 times, prior to signal-conversion thereof.

16 Claims, 4 Drawing Figures PATENIEnJum an I 3.740.937

ml 1 as 3 I INVENTOR. WILLIAM H. DRAKE BY W190i) END-DOWN DETECTING MEANS FOR AUTOMATIC YARN PIECING APPARATUS BACKGROUND OF THE INVENTION This invention relates to the end-down servicing of textile spinning frames or like machines by automatic yarn piecing apparatuses, of which various illustrative types are disclosed in US. Pat. Nos. Re. 26,230, 3,486,319, 3,498,039 and 3,540,200.

Such apparatus customarily includes a mobile carriage which moves along at least one spinning frame having a plurality of yarn delivery zones spaced longitudinally thereof. At each delivery zone which is inoperative due to the existence of an end-down or brokenyarn condition, the carriage is halted and the yarn discontinuity is eliminated, in any one of several possible ways, by suitable piecing or yarn-joining instrumentalities mounted upon the carriage. Upon completion of each piecing operation, the carriage resumes its movement and moves on to the next yarn delivery zone requiring end-down servicing.

As is apparent from the foregoing, a basic prerequisite to automatic operation of a yarn piecing apparatus is reliable detection of those yarn delivery zones at which an end-down condition exits. The present invention is directed to an improved end-down detecting means, of the type employing photoelectric components, for an automatic yarn piecing apparatus.

The use of photoelectric end-down detecting means in association with a carriage movable along one or more spinning frames has heretofore been proposed not only in association with yarn piecing apparatuses, but also in connection with end-down monitoring de vices which perform no piecing function: see, e.g., U. S. Pat. Nos. 3,099,829, 3,430,426 and 3,595,004. The requisite features of end-down detectors for such monitoring devices are not, however, precisely the same as those required in a detector for a yarn piecing apparatus. Thus, while malfunction of the detector of a mere monitoring device may cause such device to register an erroneous count and/or improperly actuate or fail to actuate an alarm, no great harm is likely to ensue from such results. On the other hand, if the end-down detector of an automatic yarn piecing apparatus malfunctions and causes such apparatus to commence a piecing operation at an improper location, extensive damage may and likely will be done to the apparatus and/or to the spinning frame being serviced. It is therefore most important that an end-down detector for an automatic yarn piecing apparatus possess a very high degree of reliability in operation, not only initially but also throughout the useful life of the apparatus. If such result is to be realized, the operation of the end-down detector for such an apparatus should rely as little as possible upon the use of mechanical-type switches, switch actuators, relays and like components which tend to fail after a period of use due to wear or, in some instances, due to exposure to the oft-times humid and lint-congested atmosphere prevalent within many textile spinning mills. The use of vacuum tubes and other expensive, delicate and or bulky components should also be avoided. The shocks and impacts generated or received by a yarn piecing apparatus, as for instance by chance encounters with movable spinning-frame cleaning equipment, tend to quickly render such components inoperative. Additionally, since a yarn piecing apparatus must of necessity carry a relatively large number of piecing instrumentalities within a confined space, and since such apparatuses cannot service as large a number of spinning frames as a mere monitoring device, the cost and size of the components employed in end-down detector are of considerable significance and must be minimized insofar as possible.

Although acceptable in end-down detectors for certain types of monitoring devices, the use of timers should also be avoided in a detector for a yarn piecing apparatus. The patroling carriage of a mere monitoring device may move continuously at a uniform velocity along each spinning frame which it services. The location of the carriage in relation to each yarn delivery zone of the spinning frame or frames may therefore be ascertained, with a degree of accuracy sufficient at least for a monitoring device, by a timing process. The carriage of a piecing apparatus, on the other hand, must necessarily decelerate and stop, and thereafter accelerate and start, at each randomly-located yarn delivery zone requiring end-down servicing. An end-down detector which determines carriage location by a timing process and by reliance upon a constant rate of carriage movement therefore does not possess the degree of reliability necessary in a yarn piecing apparatus. Due to the previously-mentioned serious consequences which are capable of ensuing from malfunction of the end-down detector of an automatic yarn piecing apparatus, it is decidedly preferable for such a detector to be a condition-responsive, rather than time-responsive, in all aspects of its operation.

While some consideration has been given various of the foregoing factors in previously proposed photoelectric end-down detectors for yarn piecing apparatuses, a need exists for such a detector which fully possesses each of the required characteristics of reliability, durability, economy and compactness.

OBJECTS OF THE INVENTION With the foregoing in mind, the primary object of the present invention is the provision, in an automatic yarn piecing apparatus, of an improved end-down detector which is highly reliable in operation both initially and after extensive use; which is of a durable construction not easily adversely affected by shocks, impacts or exposure to a humid and lint-congested atmosphere; which is economical from the viewpoint both of initial cost and subsequent maintainence; and which is of such a compact construction as to not in any way impede the mounting or operation of the various piecing instrumentalities of the apparatus.

A related and more specific object of the invention is the provision of such an end-down detector which employs solid-state and integrated-circuit electrical components, including a plurality of nand-gate coincidence units or devices, virtually exclusively, and which is free from a vacuum tubes, oscilators tuned amplifiers, mechanical switches and switch actuators, relays and similar components which would tend to detract from the desired reliability, durability, compactness, and/or economy of the detector.

Another related and more specific object is the provision, in an apparatus of the type described, of photoelectric yarn-detecting and signal-producing means comprised of a conventional light source, a standard photo-transistor device and other components of equally simple, durable, inexpensive and compact construction, which are so positioned and interconnected as to produce an operating reliability and efficiency equal or superior to that achieved with more expensive, delicate and/or bulky components such as photomultiplier tubes, modulated light sources, tuned amplifiers, and the like.

Still another object is the provision, in association with the electrical circuitry of an end-down detector for a yarn piecing apparatus, of means by which the detector can be readily disabled when desired, as for instance upon movement of the carriage of the apparatus past an end portion of a spinning frame, and thereafter can be restored with equal facility to normal operation.

SUMMARY OF THE INVENTION With the foregoing objects in mind, the present invention provides, in association with the carriage of an automatic yarn piecing apparatus movable along a textile spinning frame or like machine having a plurality of yarn delivery zones spaced along its length, first and second photoelectric signal-producing means for independently detecting whether the carriage of the apparatus is in adjacent relationship to one of the yarn delivery zones of the spinning frame and whether yarn is present within a particular area of each of such zones; a nand-gate (i.e., not and) type of control device effective when actuated to initiate a piecing operation of the apparatus, and so actuable by the coincidental receipt of actuating-type input signals at each of two input terminals thereof; and signal-correlating circuit means interconnecting the aforesaid first and second signal-producing means and the control device for actuating the latter when no yarn is detected by the second photoelectric means within a yarn delivery zone detected by the first photoelectric means. The signalcorrelating circuit includes a bistable memory device effective only when in a first operating condition to produce an actuating-type signal at one of the input terminals of the control device. Such'memory device, which is comprised of suitably interconnected nandgate units, is caused to assume or maintain its aforesaid first condition upon the detection by the first photoelectric means of the yarn delivery zone, and assumes its second condition only if yarn is detected within such zone by the second photoelectric means. The signalcorrelating means further includes a branch circuit interconnecting the other input terminal of the control device and the first photoelectric means, and effective to produce an actuating-type signal at the other input terminal of the control device upon cessation of detection of the yarn delivery zone by the first photoelectric means. If no yarn is present within the yarn delivery zone, the production of the aforesaid signal actuates the control device and thereby causes the initiation of a yarn piecing operation.

The control device and all nand-gate units of the signal-correlating means are of'intergrated circuit construction, and no mechanical switches, relays or timers are utilized.

in the preferred embodiment of the invention, inhibiting means is also provided to temporarily inhibit the memory device of the signal-correlating circuit when desired, as for instance upon movement of the carriage of the apparatus past an end portion of a spinning frame. When inhibited, the memory device is maintained in its second operating condition, irrespective of signals produced by the first photoelectric means, and

the control device is therefore rendered incapable of initiating a cycle of operation of the piecing apparatus. The inhibiting means is comprised primarily of nandgate components similar to those employed in the signal-correlating circuit, and may be placed into and out of effect with facility.

The first and second signal-producing photoelectric means each includes a standard light-producing unit, a light-receiving unit of the phototransistor type, a potentiometer for balancing the output of the phototransistor so as to compensate for ambient light conditions, and a differential amplifier for producing an electrical signal in response to variations in the balanced output of the phototransistor. In the case of the first photoelectric means, which detects whether the carriage is adjacent a yarn delivery zone of the spinning frame, the light-producing and light-receiving units may be and are mounted quite closely to the supporting track upon which the carriage of the apparatus moves along the spinning frame. A plurality of light-reflective strips, which correspond in number and spacing to the yarn delivery zones of the spinning frame, are provided upon such track. As the carriage of the piecing apparatus moves along the track, its passage into initial proximity with a yarn delivery zone of the spinning frame is reliably detected by a corresponding one of the strips reflecting the light beam of the light-producing unit to the phototransistor of the light-receiver. The cessation of reflection of light from. the strip, which occurs as the light-producing and light-receiving units continue to move with the carriage along the track, is also seen by the phototransistor and signifies with equal reliability that the carriage has passed that location within which the second photoelectric detecting means should have detected whether yarn was present within the delivery zone of the spinning frame.

The highly reliable operation of the first photoelectric means, utilizing only the conventional and relatively inexpensive components described above, is realized in large part by mounting of the light-producing and receiving units thereof in quite close confronting relationship, preferably within approximately one-half inch, to the carriage-supporting track and the reflective strips provided thereon. In the case of the second photoelectric means, which detects whether yarn is present within each delivery zone of the spinning frame, reliability of operation cannot be achieved in the same manner but nevertheless is realized without the use of bulky, highly sophisticated or expensive components.

The light-producing and light-receiving units of the second photoelectric means are similar to those described above and are adjustably mounted upon the carriage of the piecing apparatus, in vertically spaced and angularly inclined relationship to each other, for precise focusing upon an area of the spinning frame closely beneath the front or yarn-delivery pair of its drafting rolls. At such location fluctuations in the path of travel of yarn issuing from the delivery rolls, which fluctuations are occasioned by the customary vertical movement of certain of the spinning-frame components, are of minimal scope and a dead" or empty space exists rearwardly of the yarn path and between the suction-duct and roller beam of the spinning frame. To permit effective utilization of the aforesaid target stability and prominence at the location in question, the inherently narrow field of vision of the phototransistor component of the light-receiving unit is further restricted by the lense component of such unit, preferably so as to encompass an arc of only approximately four degrees. While the output of the phototransistor of the light-receiving is extremely small under the described conditions, such output provides a highly reliable indication of whether yarn is present within the field of vision of the phototransistor and is capable of being greatly amplified without the normally-attendant noise or interference problems which would otherwise frustrate such amplification. Accordingly, in accordance with the present invention, the phototransistor output is subjected to exceedingly high-gain amplification, which is preferably in the approximate order of 50,000 times and is achieved by the use of a twostage Darlington-type amplifier. The thus-amplified phototransistor output is utilized in the remainder of the circuit of the second signal-producing means in substantially the same manner as the output of the phototransistor of the first signal-producing means is employed in the previously-described circuitry thereof.

DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will be apparent from the following description of a preferred embodiment thereof, which should be read in conjunction with the accompanying drawings, in which:

FIG. 1 is a rear elevational view of an automatic yarn piecing apparatus mounted upon a fragmentarilyshown textile spinning frame or like machine and equipped with end-down detecting means in accordance with the invention;

FIG. 2 is an enlarged view, partially in elevation and partially in vertical section, taken substantially along line 2--2 of FIG. 1 and showing one set of light producing and receiving units of the end-down detecting means, together with immediately adjacent components of the piecing apparatus and the spinning frame;

FIG. 3 is an enlarged view, partially in elevation and partially in vertical section, taken substantially along line 3-3 of FIG. 1 and showing another set of light producing and receiving units of the end-down detect ing means, together with immediately adjacent components of the piecing apparatus and the spinning frame; and

FIG. 4 is a schematic showing of the electrical circuitry of the end-down detecting means.

DESCRIPTION OF THE PREFERRED EMBODIMENT The spinning machine fragmentarily shown in FIG. 1 is of a conventional type having a plurality of yarn delivery zones spaced along each of its opposite sides. At each delivery zone of machine 10 yarn as roving normally passes downwardly from creel 12 through sets of drafting rolls 14, a guide number 16, and a control ring 18 to twist-inserting collecting means in the form of a rotating spindle-bobbin assembly 20 encircled by a spinning ring 22. On the side of spinning machine 10 fragmentarily shown in FIG. 1, drafting rolls 14 are mounted upon a roller beam 24 and a conventional suction-duct 26 (also shown in FIG. 2) is provided beneath the front or delivery pair of such rolls: All spindles of the spindle-bobbin assemblies 20 are supported by a stationary spindle rail 28, while all spinning rings 22 are supported by a ring rail 30. As is well known to those skilled in the art, ring rail 30, control rings 18 and guide members 16 are moved vertically during operation of machine 10 to traverse the yarn longitudinally of spindle-bobbin assemblies 20 as it is collected thereby. The same arrangement of components is present on the opposite side of machine 10 not shown in FIG. 1.

The yarn piecing apparatus 32 shown in FIG. 1 comprises a mobile carriage 34 mounted as by a track 36 and overhead rail 38 for patrolling movement, illustratively in the leftward direction indicated by the arrow in FIG. 1, longitudinally of and closely adjacent at least the illustrated one side of spinning machine 10, to any one of its yarn delivery zones requiring servicing by reason of an end-down condition thereat. In lieu of the foregoing carriage 10 might of course be contructed so as to patrol in the opposite direction, or alternately in both directions, and normally would be so mounted as to be capable of movement along and servicing of more than a single side of one spinning machine 10.

Upon arrival of carriage 34 adjacent a yarn delivery zone of machine 10 at which an end-down condition is detected, a cycle operation of apparatus 32 is initiated. Upon initiation of each such cycle of operation, carriage 34 is halted in operative adjacent relationship to the yarn delivery zone requiring servicing, and suitable piecing instrumentalities mounted within the open center section 40 of carriage 34 repair the yarn discontinuity, after which movement of the carriage is resumed. The mechanisms and instrumentalities employed for halting carriage 34 and for repairing the yarn discontinuity may be of various types and form no part per se of the present invention, which is directed to improved means for detecting end-down conditions at the various yarn delivery zones of spinning machine 10 and for initiating the aforesaid cycles of operation of apparatus 32.

Referring now also to FIGS. 2-4, such means generally comprises first photoelectric signal-producing means, which includes the respective light-producing and light-receiving units 42,44 best shown in FIG. 3, for detecting whether carriage 34 of piecing apparatus 32 is in adjacent relationship to a yarn delivery zone of spinning machine 10; second photoelectric signalproducing means, including the respective lightproducing and light-receiving units 46,48 best shown in FIG. 2, for detecting whether yarn is present within an area of each such delivery zone closely adjacent the front or delivery pair of rolls 14 of machine 10; a nandgate control device identified in FIG. 4 by the numeral 50, effective when actuated by the coincidental receipt of actuating-type input signals at both input terminals A,B thereof to initiate a cycle of operation of apparatus 32; signal-correlating circuit means, including a pair of nand units 52,54 (FIG. 4) so interconnected as to form a bistable memory device 56, interconnecting the aforesaid first and second signal-producing means and control device 50 for actuating device 50 when no yarn is detected by units 46,48 within a yarn delivery zone detected by units 42,44; and means including additional nand units 58,60 and 62 for, when suitably actuated, inhibiting memory device 56 and thereby rendering control device 50 temporarily incapable of instituting a cycle of operation of apparatus 32. All of the various nand units are of integrated circuit construction, and illustratively are each of the type which produces a low output signal only upon the coincidental receipt of high input signals at both inputs thereof.

As is shown in FIGS. 1 & 3, light-producing and receiving units 42, 44 are mounted by a suitable bracket 64, which extends outwardly from carriage 34 in the direction of its patrolling movement, closely adjacent carriage-supporting track 36, the distance between units 42,44 and track 36 preferably being no more than approximately one-half inch. Both units 42,44 are of an inexpensive and commercially-available construction,

including a generally cylindrical housing having a lense at one end thereof. Within the housings of units 42,44 there are respectively mounted a light bulb (not shown) and a phototransistor 66 (schematically shown in FIG. 4) of standard types. Units 42, 44 are mounted in non-parallel relationship to one another (FIG. 3), such that the light beam emitted from unit 42 is received by unit 44 if reflected from the adjacent surface of track 36. T at desired times produce such reflection of the light beam, a plurality of reflective areas are provided upon the aforesaid surface of track 36, as by affixing strips 68 (FIGS. 1 & 3) of reflective tape or foil thereto. The number and spacing of strips 68 along track 36 corresponds, in a manner which will be made more apparent hereinafter, to the number and spacing of the yarn delivery zones of spinning machine 10.

Referring now to FIGS. 1 & 2, the second set of lightproducing and receiving units 46, 48 are of generally the same inexpensive and simple construction as the units 42, 44 previously described. Units 46 includes a conventional light source (not shown) within its housing, for producing unmodulated light of only medium intensity, while the housing of unit 48 encloses a conventional phototransistor 70 (schematically shown in FIG. 4). The inherently rather-limited field of vision of phototransistor 70 is further restricted by lense 72 of unit 46 so as to encompass an arc of only approximately four degrees. Brackets 74 respectively mount units 46, 48 in vertically-spaced and substantially coplanar relationship to each other at a location within section 40 of carriage 34 closely adjacent the inner wall 76 of the leading (in relation to the direction of carriage movement) side section of carriage 34. Each bracket 74 includes a first section secured to wall 76 by a bolt 78, and a second section secured to the first section by a bolt 80 and encircling the housing of the corresponding unit 46 or 48. By.loosening the bolts 76, 78

of its bracket 74, the position of either unit 46, 48 can be pivotally adjusted, as desired and independently of the other unit, about either or both of the bolt axes.

The aforesaid adjustment capability is desirable since, in accordance with the present invention, units 46,48 are precisely aimed toward a particular area of spinning machine immediately below the front or delivery pair of its drafting rolls 14. More specifically, and as is shown in FIG. 2, unit 48 is positioned so that its path of vision extends angularly downwardly toward and substantially normal to the usual path of travel of yarn issuing from delivery rolls 14, and on the opposite or rearward side of such yarn-path extends in closely adjacent but downwardly-spaced relationship to the suction duct 26 underlying delivery rolls l4 and into the "dead space between duct 26 and roller beam 24. Light-producing unit 46 directs its beam of light upwardly at an angle such as to cause any yarn present at the aforesaid location to reflect light to unit 48, and as to discourage the receipt by unit 48 of whatever light might be reflected from those components of spinning machine 10 disposed rearwardly of the yarn path of travel.

The aforesaid arrangement is significant in that fluctuations of the path of travel of yarn issuing from delivery rolls 14, which fluctuations are indicated by the dash lines in FIG. 2 and necessarily ensue from the previously-mentioned movement of certain yarnengaging components of spinning machine 10, are of a minimum magnitude closely adjacent delivery rolls 14.

The yarn closely adjacent such rolls therefore provides a target which, although quite small, is sufficiently stable as to be capable of photoelectric detection without the use of modulated and/or high-intensity light. By reason of its restrictive scope and downward inclination, the vision of unit 48 can be precisely aimed at the aforesaid relatively stable target, with minimum possibility of the unit receiving reflected light other than from yarn thereat, as from suctionduct 26 or other components of spinning machine 10. The upward inclination of unit 46, and its location in vertically spaced and substantially co-planar relationship to unit 48, also contribute to the aforesaid result. The overall effect of the foregoing is for the receipt or non-receipt of reflected light by unit 48 to accurately indicate, with an exceedingly high degree of reliability, whether yarn is or is not issuing from delivery rolls 14 at the particular location beneath their nip and along their length then viewed by unit 48.

The relative spacing of units 42,44 and 46,48 and of reflective strips 68 is such that, as carriage 34 moves into proximity with each yarn delivery zone of machine 10, light is reflected from a corresponding one of the strips 68 to unit 44 (FIG. 3). Each strip 68 is sufficiently long that light continues to be reflected therefrom to unit 44 as the further movement of carriage 34 transports units 46,48 (FIG. 2) to and through that location within the yarn delivery zone at which unit 48 will receive reflected light from yarn issuing from delivery rolls 14, if any such yarn is present within the zone. Further movement of carriage 34 transports units 42,44 beyond the aforesaid strip 68, whereupon the light beam produced by unit 42 ceases to be reflected to unit 44. If prior to the cessation of the receipt of reflected light by unit 44, the light beam produced by unit 46 was in fact reflected to unit 48 from yarn within the subject delivery zone of machine 10, carriage 34 should continue its patrolling movement without interruption. If, however, an end-down condition at the delivery zone causes the light from unit 46 to not be reflected to unit 48 prior to the passage of units 42,44 beyond reflective strip 68, a cycle of piecing operation of apparatus 32 should be instituted.

Before describing the electrical circuitry by which the foregoing results are achieved, it should be noted that units 42,44 and 46,48 are mounted forwardly, in relation to the direction of movement of carriage 34, of the piecing instrumentalities within open center section of the carriage. This permits carriage 34 to be decelerated and halted, without the necessity of reversing its movement and without subjecting any of its components to undue stress, with the aforesaid piecing instrumentalities located in desired operative relationship to the yarn delivery zone at which an end-down condition is detected in the manner described.

FIG. 4, to which reference is now made, schematically illustrates the electrical circuitry by which a piecing cycle of operation of apparatus 32 is initiated when no yarn is detected by unit 48 within a yarn delivery zone detected by unit 44. Phototransistor 66 of unit 44 forms part of a first signal-producing subcircuit shown at the lower portion of FIG. 4 and further including current-limiting fixed resistors 82, clamping diodes 84, a potentiometer 86 and a differential amplifier 88. Resistors 82 and diodes 86 protect other components of the circuit from damage by limiting the current and voltage at selected locations within the circuit to safe magnitudes. Potentiometer 86 permits balancing of the positive output voltage of phototransistor 66 against a fixed negative voltage. Potentiometer 86 is adjusted such that when photo-transistor 66 sees only ambient light, differential amplifier 88 receives a low (negative or zero) input voltage and produces a high (positive) output signal; but when phototransistor 66 receives light reflected by a strip 68 from light-producing unit 42 (FIG. 3), and thereupon increases its output, differential amplifier 88 receives a high voltage input and produces a low (negative or zero) output signal.

The second signal-producing subcircuit, which includes phototransistor 70 of unit 48 and is shown at the upper portion of FIG. 4, is similar to that described above in its inclusion of resistors 90, clamping diodes 92, a potentiometer 94, and a differential amplifier 96, all which of which perform the same basic functions as the corresponding components of the first signalproducing subcircuit. The two subcircuits differ significantly in one important respect, however. Due to the relatively shielded location of units 42,44 and their extremely close proximity to reflective strips 68 (FIGS. 1 & 3), the output of phototransistor 66 is sufficiently great to reliably insure the described production of signals by amplifier 88. The output of phototransistor 70 is, in comparison, much smaller than that of phototransistor 66, due to units 46,48 necessarily being mounted in a more exposed location and directed toward a smaller, more distant and less reflective target. As an additional component, therefore the second signalproducing circuit further includes a two-stage Darlington-type amplifier 98, which subjects the relatively weak output of phototransistor 70 to exceedingly highgain amplification, such amplification preferably being in the approximate order of 50,000 times. While it might be expected that such high-gain amplification would be frustrated by noise or background interference, such is not the case due, apparently, at least in significant part, to the vision of phototransistor 70 being restricted in scope and precisely focused as previously described herein. The thus-amplified positivevoltage output of phototransistor 70 may be and is utilized in the second signal-producing subcircuit in the same manner as the unamplified output of phototransistor 66 is employed in the first subcircuit, that is, the amplified output of phototransistor 70 is balanced by potentiometer 94 against a fixed negative voltage, such that differential amplifier 96 produces a high output when phototransistor sees only ambient light, and produces a low (negative or zero) output when the light beam of unit 46 (FIG. 2) impinges upon yarn and is re flected thereby to phototransistor 70.

Referring now particularly to the signal-correlating circuit shown in the center-right portion of FIG. 4, the output side of differential amplifier 96 is directly connected to one input of bistable memory device 56, specifically to input A of its nand unit 52, and the output nal A of control device 50. The output side of differential amplifier 88 is connected to the second input of control device by a branch circuit including signal everters 102,104 and a capacitor 106 therebetween, and is additionally connected to the second input (terminal B of nand 54) of memory device 56 through signal everter 102, input terminal B of nand unit 62, and a capacitor 107. As noted previously herein, memory device 56 is effective in a first one of its bistable operating conditions to produce an actuating-type input signal at control device 50, specifically at input A thereof, but is ineffective in the second of its operating conditions to produce an actuating-type signal at control device 50. In the present illustrative embodiment of the invention, control device 50 is actuated and initiates a cycle of piecing operation of apparatus 32 only when both inputs of the device are high, at which time its output becomes low. Memory device 56 therefore is effective in its first operating condition to produce a high input signal at terminal A of control device 50, and in its second operating condition to produce only a low signal.

Condition changes of memory device 56 of course occur only in response to signal variations at alternate ones of its two inputs (i.e., input A of nand 52 and input B of nand 54). Thus, if device 56 changed from its first to its second bistable condition in response to a signal variation at input A of its nand 52, a change back to its first bistable condition is producible only by a signal variation at input B of its nand 54. It therefore follows that by prohibiting variations in the signal at its aforesaid terminal B, memory device 56 can be inhibited and prevented from assuming its first operating condition.

As has been previously noted, nand 62 comprises part of means for inhibiting, as aforesaid and at desired times, memory device 56. Such inhibiting means further includes (see the left-center portion of FIG. 4) a second memory device 112, which is similar to memory device 56 and is comprised of suitably interconnected nand-gates 58,60, and a pair or normally-open switch elements 114,116. The output of memory device 112 is normally high, and is received by input A of nand 62. Closure of switch 114 grounds one input (terminal B of nand of device 112, thereby changing its output to low and producing the desired inhibiting action in a manner described more fully hereinafter, and simultaneously grounds one input (terminal A of nand 52) of I memory device 52. Closure of switch 116 grounds the of device 56 is directed to and received by input termiother input (terminal A of nand 58) of device 112 and resets the same by thereby causing its output to again become high.

OPERATION OF THE PREFERRED EMBODIMENT While carriage 34 of apparatus 32 is intermediate delivery zones of spinning machine 10 and phototransistors 66, are therefore both receiving only ambient light, the outputs of amplifiers 88,96 are both high, as noticed previously herein. The signal-conditions elsewhere in the FIG 4 circuit at this time are as follows. Both inputs of nand 58 are high, which causes its output and input A of nand 60 to be low. Input B of nand 60 is high, as is its output and therefore input A of nand 62. Input B of nand 62 is low, as required by the then high input to everter 102 and its consequential low output. The combination of high and low inputs to nand 62 causes its output to be high. Both inputs of nand 54 of memory device 56 are high, which causes its output and the input at terminal A of control device 50 to be low: that is, memory device 56 is in its second operating condition. Input A of nand 52 is high, in accordance with the then high output of amplifier 96, while input B of nand 52 is low, in accordance with the output of nand 54. The output of nand 52 of course has the same condition, that is high, as input A of nand 54. The input to everter 104 is high, this being possible notwithstanding the then low output of everter 102 due to the capacitor 106 therebetween, which causes the output of everter 104 and input B of control device 50 to be low. Since both inputs of control device 50 are low, its output is high and ineffective to initiate a cycle of operation of apparatus 32. As noted previously, device 50 initiates a cycle of operation only upon a coincidental receipt of high input signals at both of its input terminals, at which time its output becomes low.

When movement of carriage 34 brings units 42,44 to a position where light is reflected from the former to the latter by one of the reflective strips 68 (FIG. 3), the output of amplifier 88 and therefore the input to everter 102 change from high to low. This change in input of everter 102 changes its output, and therefore input B of nand 62, from low to high. The combination of two high inputs at nand 62 changes its output from high to low, whereupon capacitor 107 discharges. This in turn causes input B of nand 54 of memory device 56 to momentarily change from high to low, whereupon memory device 56 assumes its first bistable operating condition and produces a high or actuating-type input at terminal A of control device 50. The output of control device 50 does not change, however, since input B thereof remains low due to the continued low output of everter 104.

Further movement of carriage next brings units 46,48 to a position where light is reflected from the former to the latter by yarn issuing from delivery rolls 14 (FIG. 2), if any such yarn is present within the delivery zone in question. Assuming yarn is present, the output of amplifier 96 and therefore the input to terminal A of nand 52 of memory device 56 change from low to high. This causes memory device 56 to again assume its second operating condition and produce a low input at terminal A of control device 50. The combination of two low inputs at control device 50 of course does not change its output, which remains high.

Due to the continued movement of carriage 34, the aforesaid yarn is only momentarily within the field of vision of phototransistor 70 of light-receiving unit 48. The output of amplifier 96 therefore quickly again becomes high, as phototransistor 70 sees only ambient light. The resulting high input at terminal A of nand 52 of memory device 56 does not cause another change in the operating condition of the memory device, however, since the immediately-preceding condition change of device 56 resulted from a signal variation at the same input thereof.

The final step in the sequence of operation occurs as continued movement of carriage 34 transports units 42,44 beyond the reflective strip 68 theretofore reflecting light from the former unit to the latter one. When this occurs the output of amplifier 88, and therefore the input of everter 102, change to high. The output of everter 102, and therefore input B of nand 62, change to low. The then-present combination of high and low inputs at nand 62 causes its output to become high. Since capacitor 107 does not discharge, however, no

signal variation occurs at input terminal B of nand 54 of control device 56. Device 56 therefore remains in its second operating condition, and input A of control de vice 50 remains low. The output of control device 50 thus remains high, even though input B thereof momentarily changes to high as the previously noted change in output of everter 102, from high to low, causes capacitor 106 to discharge and thereby produces a momentary low input and high output at everter 104.

Following recharging of capacitor 106, which transpires immediately and automatically after its aforesaid discharge, the entire FIG. 4 circuit is again in its original state and therefore is ready for passage-of carriage 34 into proximity with the next-adjacent yarn delivery zone of machine 10.

At a yarn delivery zone whereat an end-down condition exists, the first of the previously-described changes in the state of the FIG. 4 circuit will again occur. That is, the change to low in the output of amplifier 88, resulting from phototransistor 66 seeing" the reflective strip 68 associated with the yarn delivery zone, causes memory device 56 to assume its first operating condition and produce a high input at terminal A of control device 50. No further changes occur as further movement of carriage 34 transports units 46,48 through that location within the zone at which yarn would normally by seen by phototransistor 70 of unit 48, due to the end-down condition within the zone. Input A of control device 50 is therefore still high when phototransistor 66 no longer sees reflective strip 68, and input B of control device 50 momentarily goes high. The coincidental receipt of two high inputs actuates control device 50, which produces a low output effective to initiate a cycle of operation of piecing apparatus 32 at the yarn delivery zone requiring end-down servicing.

As noted previously herein, the locations of units 42,44 and 46,48 upon carriage 34 of apparatus 32 are such as to permit carriage 34 to be non-abruptly decelerated and halted, upon the detection as aforesaid of an end-down, with its centrally-mounted piecing instrumentalities in proper operative relationship to'the yarn delivery zone requiring servicing. Reverse movement of carriage 34 is not required.

Upon the completion by apparatus 32 of the piecing operation and the resumption of movement of its carriage 34, the overall state of the FIG. 4 circuit will be the same as that ordinarily possessed by it only immediately after phototransistor 66 sees a reflective strip 68. That is, memory device 56 will be in its first operating condition. This does change the previously described sequence of operation, however, except in the fact that memory device 56 merely maintains, rather than assumes, its first operating condition when phototransistor 66 sees the next reflective strip 68.

Momentary closure of double-contact switch 1 l4 disables the FIG. 4 circuit and prohibits all possability at desired times, as when carriage 34 is moving past an end of spinning machine 10, of a cycle of operation of apparatus 32 being instituted. The closure of one contact of switch 114 grounds and therefore produces a low signal at input A of nand 52 of memory device 56. Such signal causes memory device 56 to assume its second operating condition if, contrary to the normal situation, the memory device is not already in its second condition. The simultaneous closure of the other contact of switch 114 grounds and therefore produces a low signal at input B of memory device 112. This causes the output of device 112, and therefore input A of nand 62, to change from high to low. For so long as input A of nand 62 remains low, its output and therefore input B of nand 54 of memory device 56 must remain high, irrespective of variations in the signals produced by amplifier 88. Memory device 56 is therefore inhibited and prevented from assuming its first bistable operating condition, and control device 50 cannot be actuated.

Termination of the period of inhibition of memory device 56 is effected, when desired and with equal facility, by momentary closure of reset switch 116. This grounds and produces a low input at terminal A of nand 58 of device 112, causing the output of device 112 and input A of nand 62 to change once again to high. Switches 114,116 may of course be constructed for automatic actuation, at desired times and as by suitable photoelectric means (not shown) provided in association therewith, in a particular use-environment of apparatus 32.

While a preferred embodiment of the invention has been 'shown and described, this was for purposes of illustration only, and not for purposes of limitation.

That which is claimed is:

1. In an automatic yarn piecing apparatus adapted to service a textile spinning frame having a plurality of horizontally spaced yarn delivery zones whereat yarn normally passes downwardly from delivery rolls and past a suction duct to yarn collecting means, said apparatus including a carriage adapted to move along said spinning frame and to be halted upon institution of piecing operations adjacent yam-delivery zones requiring servicing by reason of an end-down condition thereat, improved means for detecting said end-down conditions and for initiating said piecing operations, comprising:

first photoelectric signal-producing means for detecting whether said carriage is adjacent a yarn delivery zone of said spinning frame;

second photoelectric signal-producing means for detecting whether yarn is present within an area of each said zone closely adjacent said delivery rolls of said spinning frame;

a nand-gate control device effective when actuated to produce an output signal initiating a piecing operation, said device having a pair of input terminals and being actuated by the coincidental receipt of actuating-type input signals at each of said terminals;

and signal-correlating circuit means interconnecting said first and second signal-producing means and said control device for actuating said control device when no yarn is detected by said second means within a yarn delivery zone detected by said first means.

2. Apparatus as in claim 1, wherein said signalcorrelating means includes a bistable memory device effective in a first operating condition to produce an actuating-type signal at one of said input terminals of said control device and ineffective in a second operating condition to produce an actuating-type signal at said one input terminal of said control device; said memory device assuming or maintaining said first condition thereof upon detection by said first means of a yarn delivery zone and assuming said second condition upon yarn-detection by said second means.

3. Apparatus as in claim 2, wherein said signalcorrelating means further includes a branch circuit interconnecting the other of said input terminals of said control device and said means for producing an actuating-type signal at said other input terminal of said control device upon cessation of the detection of a yarn delivery zone by said first means.

4. Apparatus as in claim 3, wherein said branch circuit includes capacitor means and signal-everting means for limiting the time of production of said actuating-type signal at said other input terminal of said control device.

5. Apparatus as in claim 2, and further including inhibiting means effective when actuated to inhibit said memory device and maintain the same in said second condition thereof irrespective of signals produced by said first signal-producing means.

6. Apparatus as in claim 5, wherein said inhibiting means includes a nand-type unit within that portion of said signal-correlating circuit interconnecting said first signal-producing means and said memory device, said nand-type unit normally varying its output in response to signal variations of said first means and upon actuation of said inhibiting means being rendered unresponsive to signal-variations of said first means.

7. Apparatus as in claim 6, wherein said nand-type unit has a pair of input terminals and said first signalproducing is connected to one of said input terminals, and wherein said inhibiting means further includes a bistable memory unit connected to the other of said input terminals of said nand-type unit, said nand-type unit varying its output in response to signal-variations of said first means when said memory unit is in a first operating condition and said nand-type unit being unresponsive to signal-variations of said first means when said memory unit is in a second operating condition, and switch means for varying as desired the operating condition of said memory unit.

8. Apparatus as in claim 1, wherein said second signal-producing means includes a light-producing unit and a light-receiving unit mounted upon said carriage in vertically-spaced relationship to each other, the path of vision of said light-receiving unit extending through and substantially normal to the ordinary path of travel of yarn issuing from said delivery rolls of said spinning frame and projecting beyond said path of travel in closely adjacent but downwardly-spaced relationship to said suction duct of said spinning frame.

9. Apparatus as in claim 8, including means mounting said light-receiving unit and said light-producing unit upon said carriage for independent positional adjustment of each said unit about either of two axes.

10. Apparatus as in claim 8, wherein said lightreceiving unit comprises a phototransistor device having a narrow field of vision, and lense means for further narrowing said field of vision of said phototransistor device.

11. Apparatus as in claim 10, wherein said second signal-producing means further includes Darlingtontype amplifier means for subjecting the output of said phototransistor device to high-gain amplification.

12. Apparatus as in claim 11, wherein the high-gain amplification of said output of said phototransistor device is in the approximate order of 50,000.

13. Apparatus as in claim 11, wherein said second signal-producing means further includes potentiometer means for balancing the output of said Darlington-type amplifier as required to compensate for ambient light conditions at said phototransistor device, and a signalproducing differential amplifier connected in series with said Darlington-type amplifier and responsive to uncompensated for variations in output thereof.

14. Apparatus as in claim 1, and further including track means carried by an extending longitudinally of said spinning frame and mounting said carriage of said piecing apparatus for movement therealong, light reflecting means upon said track means corresponding in number and spacing to said yarn delivery zones of said spinning frame, said first signal-producing means including a light-producing unit and a light-receiving unit mounted upon said carriage in closely adjacent confronting relationship to said track means for cooperation with said reflecting means during movement of said carriage along said track means.

15. Apparatus as in claim 14, within said lightreceiving means includes a phototransistor, and said first signal-producing means includes potentiometer means balancing the output of said phototransistor to compensate for ambient light conditions thereat, and a differential amplifier connected in series with said phototransistor and responsive to uncompensated for variations in said output.

16. Apparatus as in claim 14, wherein said reflecting means comprises a reflective strip for each of said delivery zones of said spinning machine, and said signalproducing means is responsive to movement of said units thereof both into and out of confronting relationship with each said reflective strip. 

1. In an automatic yarn piecing apparatus adapted to service a textile spinning frame having a plurality of horizontally spaced yarn delivery zones whereat yarn normally passes downwardly from delivery rolls and past a suction duct to yarn collecting means, said apparatus including a carriage adapted to move along said spinning frame and to be halted upon institution of piecing operations adjacent yarn-delivery zones requiring servicing by reason of an end-down condition thereat, improved means for detecting said end-down conditions and for initiating said piecing operations, comprising: first photoelectric signal-producing means for detecting whether said carriage is adjacent a yarn delivery zone of said spinning frame; second photoelectric signal-producing means for detecting whether yarn is present within an area of each said zone closely adjacent said delivery rolls of said spinning frame; a nand-gate control device effective when actuated to produce an output signal initiating a piecing operation, said device having a pair of input terminals and being actuated by the coincidental receipt of actuating-type input signals at each of said terminals; and signal-correlating circuit means interconnecting said first and second signal-producing means and said control device for actuating said control device when no yarn is detected by said second means within a yarn delivery zone detected by said first means.
 2. Apparatus as in claim 1, wherein said signal-correlating means includes a bistable memory device effective in a first operating condition to produce an actuating-type signal at one of said input terminals of said control device and ineffective in a second operating condition to produce an actuating-type signal at said one input terminal of said control device; said memory device assuming or maintaining said first condition thereof upon detection by said first means of a yarn delivery zone and assuming said second condition upon yarn-detection by said second means.
 3. Apparatus as in claim 2, wherein said signal-correlating means further includes a branch circuit interconnecting the other of said input terminals of said control device and said means for producing an actuating-type signal at said other input terminal of said control device upon cessation of the detection of a yarn delivery zone by said first means.
 4. Apparatus as in claim 3, wherein said branch circuit includes capacitor means and signal-everting means for limiting the time of production of said actuating-type signal at said other input terminal of said control device.
 5. Apparatus as in claim 2, and further including inhibiting means effective when actuated to inhibit said memory device and maintain the same in said second condition thereof irrespective of signals produced by said first signal-producing means.
 6. Apparatus as in claim 5, wherein said inhibiting means includes a nand-type unit within that portion of said signal-correlating circuit interconnecting said first signal-producing means and said memory device, said nand-type unit normally varying its output in response to signal variations of said first means and upon actuation of said inhibiting means being rendered unresponsive to signal-variations of said first means.
 7. Apparatus as in claim 6, wherein said nand-type unit has a pair of input terminals and said first signal-producing is connected to one of said input terminals, and wherein said inhibiting means further includes a bistable memory unit connected to the other of said input terminals of said nand-type unit, said nand-type unit varying its output in response to signal-variations of said first means when said memory unit is in a first operating condition and said nand-type unit being unresponsive to signal-variations of said first means when said memory unit is in a second operating condition, and switch means for varying as desired the operating condition of said memory unit.
 8. Apparatus as in claim 1, wherein said second signal-producing means includes a light-producing unit and a light-receiving unit mounted upon said carriage in vertically-spaced relationship to each other, the path of vision of said light-receiving unit extending through and substantially normal to the ordinary path of travel of yarn issuing from said delivery rolls of said spinning frame and projecting beyond said path of travel in closely adjacent but downwardly-spaced relationship to said suction duct of said spinning frame.
 9. Apparatus as in claim 8, including means mounting said light-receiving unit and said light-producing unit upon said carriage for independent positional adjustment of each said unit about either of two axes.
 10. Apparatus as in claim 8, wherein said light-receiving unit comprises a phototransistor device having a narrow field of vision, and lense means for further narrowing said field of vision of said phototransistor device.
 11. Apparatus as in claim 10, wherein said second signal-producing means further includes Darlington-type amplifier means for subjecting the output of said phototransistor device to high-gain amplification.
 12. Apparatus as in claim 11, wherein the high-gain amplification of said output of said phototransistor device is in the approximate order of 50,000.
 13. Apparatus as in claim 11, wherein said second signal-producing means further includes potentiometer means for balancing the output of said Darlington-type amplifier as required to compensate for ambient light conditions at said phototransistor device, and a signal-producing differential amplifier connected in series with said Darlington-type amplifier and responsive to uncompensated for variations in output thereof.
 14. Apparatus as in claim 1, and further including track means carried by an extending longitudinally of said spinning frame and mounting said carriage of said piecing apparatus for movement therealong, light reflecting means upon said track means corresponding in number and spacing to said yarn delivery zones of said spinning frame, said first signal-producing means including a light-producing unit and a light-receiving unit mounted upon said carriage in closely adjacent confronting relationship to said track means for cooperation with said reflecting means during movement of said carriage along said track means.
 15. Apparatus as in claim 14, within said light-receiving means iNcludes a phototransistor, and said first signal-producing means includes potentiometer means balancing the output of said phototransistor to compensate for ambient light conditions thereat, and a differential amplifier connected in series with said phototransistor and responsive to uncompensated for variations in said output.
 16. Apparatus as in claim 14, wherein said reflecting means comprises a reflective strip for each of said delivery zones of said spinning machine, and said signal-producing means is responsive to movement of said units thereof both into and out of confronting relationship with each said reflective strip. 